Adequate sunshine, water, and fertilizer plus a well-drained growing medium are essential for successful container gardens.

ContainersAlmost any type of container can be used if it provides good drainage through holes in the bottom or around the sides near the bottom. If adding holes, drill four or more 1⁄1⁄1

4⁄4⁄ -inch holes evenly spaced around the container bottom.

To further help drainage, put about 1⁄1⁄12⁄2⁄ inch of coarse gravel,

small stones, or pieces of a broken clay pot in the bottom. These items are not a substitute for drainage holes.

Most vegetables require containers that hold at least 6 to 8 inches of potting mix. Root crops,such as carrots, and tomatoes and other larger plants require deeper containers. See Table 1 for the amount of potting mix needed to fi ll various sized containers. See Table 2 for the approximate size containers recommended for various vegetables.

For longer life, wood containers should be constructed of the heartwood of naturally durable tree species, such as western red cedar and redwood, or from lumber that has been pressure-treated with arsenic-free wood preservatives. Examples include alkaline copper quat (ACQ) and copper azole (CBA-A and CA-B). For maximum durablity and service life, the pressure-treated wood should be labeled “End Use-Ground Contact.” A manageable size is 18 inches x 24 inches x 8 inches. Drainage holes must be drilled in the bottom or around the sides near the bottom. A mesh screen can be cut to fi t the bottom of the container to allow water, but not soil, to drain.

Growing mediaContainer gardens require a growing medium that drains well, yet does not dry out too fast. Soilless potting mixes have several advantages over soil. They are free of plant disease organisms and weed seeds, are less likely to compact, hold moisture and plant nutrients well, and are lightweight—making the container more portable.

PM 870B Revised May 2005

Container vegetable gardeningSoilless potting mixes can be purchased from garden centers and retail outlets or they can be prepared using the proportions in Table 3.

Crop selectionMost vegetables that grow in a backyard garden will do well as container-grown plants. Those with compact growth habits will do best. See Table 4 for suggested cultivars.

Summer care of container gardensLocation—Nearly all vegetables grow and produce best when grown in full sunlight. Plants that bear fruit, such as cucumbers, tomatoes, peppers, and eggplant, require the most sun. Leafy vegetables (lettuce, cabbage, greens, spinach, and parsley) tolerate more shade than root crops (radishes, beets, and onions). Containers should be placed where they will receive at least 6 hours of sunlight per day.

Watering—Plants grown in containers require frequent watering because they dry out quickly from sun and wind. Some plants may require daily watering. Apply enough water to reach the bottom of the container and allow the excess to drain through the drainage holes. Never allow the soil to dry out completely between waterings; this may cause the plants to drop their fruits and fl owers. However, over-watering also will slowly kill plants because the roots will not receive enough oxygen. When watering, avoid wetting the leaves, especially if watering late in the day. Wet leaves encourage the development of plant diseases.

Fertilization—Container-grown plants require fertilization more frequently than fi eld-grown vegetables because they have less soil from which to obtain nutrients. A soluble fertilizer (15-30-15 or 20-20-20) applied once every week or two is recommended. This can be applied while watering.

Tomato tips—When growing standard-sized tomato —When growing standard-sized tomato —varieties, use a stake or cage to keep the vines upright. If staked, plants should be pruned to produce manageable one- or two-stem plants. To prune a tomato, remove the small shoots that form in the axils of the leaves and stems. If these shoots are not pinched out, they will grow and make the plants diffi cult to train. Tie the stems loosely to the stake. Tomato cages should be made of fencing material of at least 4-inch mesh so the fruit can be harvested easily. Cages should be at least 24 inches in diameter.

Table 1. Pot size and capacity

Diameter inside Approximate Diameter inside Approximate top (inches) soil content top (inches) soil content

3 1 cup 3 1 cup

4 2 4 21⁄1⁄12⁄2⁄ cups

5 1 quart 5 1 quart

6 2 6 21⁄1⁄12⁄2⁄ quarts

7 3 quarts 7 3 quarts

8 1 gallon 8 1 gallon

9 1 9 11⁄1⁄12⁄2⁄ gallons

10 2 10 21⁄1⁄14⁄4⁄ gallons4 gallons4

12 3 12 31⁄1⁄12⁄2⁄ gallons

14 6 gallons 14 6 gallons

Table 3. Soilless potting mix recipe

Materials To make 2 bushels Materials To make 2 bushels

Shredded sphagnum peat moss 1 bushel Shredded sphagnum peat moss 1 bushel Vermiculite 1 bushel Vermiculite 1 bushel Ground limestone 1 Ground limestone 11⁄1⁄1

4⁄4⁄ cups4 cups4

Superphosphate (0-20-0) Superphosphate (0-20-0) 1⁄1⁄12⁄2⁄ cup

or Superphosphate (0-45-0) or Superphosphate (0-45-0) 1⁄1⁄14⁄4⁄ cup4 cup4

Granular 5-10-5 fertilizer 1 cup Granular 5-10-5 fertilizer 1 cup

Moisten with water; store in plastic garbage bags. Moisten with water; store in plastic garbage bags.

Table 4. Suggested vegetable cultivars for container gardens

Beets Ruby Queen Beets Ruby Queen

Carrots Little Finger, Danver’s Half Long, Carrots Little Finger, Danver’s Half Long, Nantes Half Long Nantes Half Long

Cucumber Salad Bush, Bush Champion, Cucumber Salad Bush, Bush Champion, Spacemaster Spacemaster

Eggplant Dusky Eggplant Dusky

Green beans Topcrop, Tendercrop, Derby Green beans Topcrop, Tendercrop, Derby

Lettuce Green Ice, Salad Bowl, Red Sails, Lettuce Green Ice, Salad Bowl, Red Sails, Black Seeded Simpson, Buttercrunch, Black Seeded Simpson, Buttercrunch, Oakleaf Oakleaf

Parsley Dark Moss Curled, Paramount Parsley Dark Moss Curled, Paramount

Pepper Lady Bell, Gypsy, Crispy, New Ace, Pepper Lady Bell, Gypsy, Crispy, New Ace, Bell Boy, Red Chili (hot) Bell Boy, Red Chili (hot)

Radishes Champion, Comet, Sparkler, White Radishes Champion, Comet, Sparkler, White Icicle, Early Scarlet Globe Icicle, Early Scarlet Globe

Spinach American Viking, Long Standing Spinach American Viking, Long Standing Bloomsdale, Melody Bloomsdale, Melody

Summer squash Pic-N-Pic (yellow crookneck) Summer squash Pic-N-Pic (yellow crookneck)

Swiss chard Fordhook Giant (white ribbed), Swiss chard Fordhook Giant (white ribbed), Lucullus (green ribbed) Lucullus (green ribbed)

Tomatoes Tomatoes Standard Jetstar, Celebrity, Super Bush Standard Jetstar, Celebrity, Super Bush Patio Patio Patio Patio Cherry Pixie Cherry Pixie

Table 2. Container size for vegetables

Minimum No. of plants Minimum No. of plants Crop size per container Crop size per container

Beets 2 gallon Thinned to 2-3 inches apart

Cabbage 1 gallon 1 plant Cabbage 1 gallon 1 plant

Carrots 2 gallon Thinned to 2-3 inches apart Carrots 2 gallon Thinned to 2-3 inches apart

Cucumber 1 gallon 2 plants Cucumber 1 gallon 2 plants

Eggplant 2 gallon 1 plant Eggplant 2 gallon 1 plant

Green beans 1 gallon 2-3 plants Green beans 1 gallon 2-3 plants

Leaf lettuce 1 gallon 4-6 plants Leaf lettuce 1 gallon 4-6 plants

Parsley Parsley 1⁄1⁄12⁄2⁄ gallon 1 plant

Pepper 2 gallon 2 plants Pepper 2 gallon 2 plants

Radishes 2 gallon Thinned to 1-2 inches apart Radishes 2 gallon Thinned to 1-2 inches apart

Spinach 1 gallon Thinned to 3 inches apart Spinach 1 gallon Thinned to 3 inches apart

Swiss chard 1 gallon 1 plant Swiss chard 1 gallon 1 plant

Tomatoes Tomatoes Cherry 1 gallon 1 plant Cherry 1 gallon 1 plant Standard 3 gallon 1 plant Standard 3 gallon 1 plant

. . . and justice for allThe U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status. (Not all prohibited bases apply to all programs.) Many materials can be made available in alternative formats for ADA clients. To fi le a complaint of discrimination, write USDA, Offi ce of Civil Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Stanley R. Johnson, director, Cooperative Extension Service, Iowa State University of Science and Technology, Ames, Iowa.

Prepared by Richard Jauron, extension horticulturist and Diane Nelson, extension communication specialist. Illustrations by Jane Lenahan, extension graphic designer.

File: Hort and LA 2-9

For more informationAdditional information about vegetable gardening and other horticultural topics is available from local extension offi ces and from these Web sites:

ISU Extension Distribution Center (online store)—www.extension.iastate.edu/store

ISU Extension Horticulture—www.yardandgarden.extension.iastate.edu

ISU Extension Publications—www.extension.iastate.edu/pubs